The present invention relates to a silver halide light-sensitive material containing a tanning developing agent. The invention also relates to a tanning developing solution and a lithographic printing plate.
Tanning development has been well known in the field of a silver halide photography. For example, T. H. James, The Theory of the Photographic Process, 4th edition, pages 326 to 327 describes the tanning development in detail. When a silver halide light-sensitive material is developed with a phenol type developing agent, such as pyrogallol, hydroquinone or catechol, gelatin of a silver halide emulsion layer is hardened within an exposed area of the emulsion. This phenomenon is referred to as a tanning effect, which is caused by an oxidation product of the phenol type developing agent.
Tanning effect gives soft gradation to a silver halide photographic image. Since the hardened gelatin within the exposed area prevents a developing solution from further penetrating into a silver halide emulsion layer, the development is inhibited within the exposed area.
The tanning effect can also be used to form a relief image. After gelatin is hardened within the exposed area, unhardened gelatin in the unexposed area can be removed form the layer to form a relief image of hardened gelatin.
The relief image of hardened gelatin can be used as a lithographic printing plate. If the relief image of hardened gelatin is formed on a hydrophilic support (such as an aluminum plate), the area of the support surface (where unhardened gelatin was removed) works as hydrophilic area. On the other hand, the area where the relief is formed works as oleophilic area. Dampening water is attached on the hydrophilic area, and oily ink is attached on oleophilic area in the lithographic printing process.
Japanese Patent Provisional Publication Nos. 53(1978)-135702, 54(1979)-49202, 54(1979)-152502, 55(1980)-126250, 4(1992)-324866 and 5(1993)-289228 describe a lithographic printing process using a relief image of hardened gelatin as a printing plate.
The lithographic printing plate of hardened gelatin relief image has an advantage that silver halide works as a highly sensitive photosensor. The lithographic printing plate has another advantage that the plates can be can be prepared by a simple process compared with other conventional printing plates.
When the relief image of hardened gelatin is used as a lithographic printing plate, the area of the support surface works as hydrophilic area, and the area where the relief is formed works as oleophilic area. Though the hardened gelatin is relatively oleophilic as compared with the support surface, the gelatin itself is not strongly oleophilic. Moreover, the hardened gelatin is often referred to as a hydrophilic substance. The hardened gelatin sometimes absorbs dampening water in the lithographic printing process. The hardened gelatin swells or is softened (or weakened) with the dampening water.
Poorly oleophilic hardened gelatin often causes a trouble of a poor affinity with ink when the relief image of hardened gelatin is used as a lithographic printing plate. Further, weak hardened gelatin often causes a trouble of poor printing durability.
Japanese Patent Publication Nos. 53(1978)-135702, 54(1979)-49202, 54(1979)-152502, 55(1980)-12625, 4(1992)-324866 and 5(1993)-289228 propose that the hardened gelatin be subjected to treatments (a heat treatment, a light irradiation treatment, a chemical treatment) after forming the relief image to improve the ink affinity and the printing durability. However, the post-treatments mar the advantage of a simple process. The heat treatment often lowers the adhesion between the hardened gelatin and the support. The light irradiation treatment needs a strong light-irradiating apparatus. The chemical substances used in the chemical treatment have toxicity and hardly give satisfying effects.
An object of the present invention is to form highly oleophilic and highly durable hardened gelatin by using a new tanning developing agent.
The first embodiment of the present invention provides a silver halide light-sensitive material comprising a support amd a silver halide gelatin emulsion layer, wherein the silver halide gelatin emulsion layer or an optionally provided hydrophilic layer contains a tanning developing agent having a molecular structure in which two to six benzenediol or benzenetriol rings are connected with a linking group.
The first embodiment also provides a tanning developing solution consisting of an aqueous alkali solution of a tanning developing agent having a molecular structure in which two to six benzenediol or benzenetriol rings are connected with a linking group.
The first embodiment further provides a process for preparation of a lithographic printing plate comprising the steps in order of: imagewise exposing to light a silver halide light-sensitive material comprising a hydrophilic support and a silver halide gelatin emulsion layer, subjecting the silver halide light-sensitive material to tanning development to harden gelatin within an exposed area by using a tanning developing agent having a molecular structure in which two to six benzenediol or benzenetriol rings are connected with a linking group; and removing unhardened gelatin within unexposed area from the silver halide gelatin emulsion layer to form a relief image of the hardened gelatin on the hydrophilic support.
The first embodiment furthermore provides a lithographic printing plate comprising a relief image of a hardened gelatin on a hydrophilic support, wherein the gelatin is hardened by an oxidation product of a tanning developing agent having a molecular structure in which two to six benzenediol or benzenetriol rings are connected with a linking group.
The second embodiment of the invention provides a silver halide light-sensitive material comprises a support and a silver halide gelatin emulsion layer, wherein the silver halide gelatin emulsion layer or an optionally provided hydrophilic layer contains a tanning developing agent consisting of a polymer having side chains containing benzenediol or benzenetriol rings.
The second embodiment also provides a tanning developing solution consisting of an aqueous alkali solution of a tanning developing agent consisting of a polymer having side chains containing benzenediol or benzenetriol rings
The second embodiment further provides a process for preparation of a lithographic printing plate comprising the steps in order of: imagewise exposing to light a silver halide light-sensitive material comprising a support and a silver halide gelatin emulsion layer, subjecting the silver halide light-sensitive material to tanning development to harden gelatin within an exposed area by using a tanning developing agent consisting of a polymer having side chains containing benzenediol or benzenetriol rings; and removing unhardened gelatin within unexposed area from the silver halide gelatin emulsion layer to form a relief image of the hardened gelatin on the hydrophilic support.
The second embodiment furthermore provides a lithographic printing plate comprising a relief image of a hardened gelatin on a hydrophilic support, wherein the gelatin is hardened by an oxidation product of a tanning developing agent consisting of a polymer having side chains containing benzenediol or benzenetriol rings.
The third embodiment of the invention provides a process for preparation of a lithographic printing plate comprising the steps in order of: imagewise exposing to light a silver halide light-sensitive material comprising a support and a silver halide gelatin emulsion layer, subjecting the silver halide light-sensitive material to tanning development to harden gelatin within an exposed area by using a phenol compound represented by the formula (II); and removing unhardened gelatin within unexposed area from the silver halide gelatin emulsion layer to form a relief image of the hardened gelatin on the hydrophilic support: 
in which p is 1 or 2; and R is an aliphatic group having 5 to 40 carbon atoms, an aromatic group having 7 to 40 carbon atoms, an aliphatic acyl group having 5 to 40 carbon atoms, an aromatic acyl group having 7 to 40 carbon atoms, an aliphatic oxycarbonyl group having 5 to 40 carbon atoms, an aromatic oxycarbonyl group having 7 to 40 carbon atoms, an aliphatic acyloxy group having 5 to 40 carbon atoms, an aromatic acyloxy group having 7 to 40 carbon atoms, an aliphatic carbamoyl group having 5 to 40 carbon atoms or an aromatic carbamoyl group having 7 to 40 carbon atoms.
The third embodiment also provides a lithographic printing plate comprising a relief image of a hardened gelatin on a hydrophilic support, wherein the gelatin is hardened by a phenol compound represented by the formula (II).
The present inventors have searched and developed an improved tanning developing agent in place of adding a post-treatment proposed in the prior art references. As a result, the inventors have succeeded in preparing a highly oleophilic and highly durable hardened gelatin with a new tanning developing agent. The first embodiment of the present invention uses a compound having a molecular structure in which two to six benzenediol or benzenetriol rings are connected with a linking group. The second embodiment of the invention uses a polymer having side chains containing benzenediol or benzenetriol rings. The third embodiment uses a compound consisting of a benzenediol or benzenetriol ring having an aliphatic substituent group having 5 to 40 carbon atoms or an aromatic substituent group having 7 to 40 carbon atoms. The benzenediol or benzenetriol ring corresponds to a conventional tanning developing agent (e.g., pyrogallol, hydroquinone or catechol). The prepared hardened gelatin is oleophilic and durable enough to be used as a lithographic printing plate. The lithographic printing plate of hardened gelatin relief image has an advantage that silver halide is used as a highly sensitive photosensor. The printing plate has another advantage that the plate can be prepared by a simple process.